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EstimOting . I_1 one participation for the ~1 C Program Final Report Panel to Evaluate the USDA:s Methodology for Estimating Eligibility and Participation for the WIC Program Michele Ver Ploeg and David M. Betson, Editors Committee on National Statistics Division of Behavioral and Social Sciences and Education NATIONAL RESEARCH COUNCIL OF DIE NATIONAL ACADEMIES TH E NATIONAL ACADEMI ES PRESS Washington' D.C. www.nap.edu
THE NATIONAL ACADEMIES PRESS 500 Fifth Street, N.W. Washington, DC 20001 NOTICE: The project that is the subject of this report was approved by the Governing Board of the National Research Council, whose members are drawn from the councils of the National Academy of Sciences, the National Academy of Engineering, and the Institute of Medicine. The members of the committee responsible for the report were chosen for their special competences and with regard for appropriate balance. This study was supported by Contract/Grant No.53-3198-0-012 between the National Academy of Sciences and the United States Department of Agriculture. Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the authorks) and do not necessarily reflect the views of the organizations or agencies that provided support for the project. International Standard Book Number 0-309-08962-X (Book) International Standard Book Number 0-309-52551-9 (PDF) Library of Congress Control Number 2003109822 Additional copies of this report are available from National Academies Press, 500 Fifth Street, N.W., Lockbox 285, Washington, DC 20055; (800) 624-6242 or (202) 334- 3313 (in the Washington metropolitan area); Internet, http://www.nap.edu. Printed in the United States of America. Copyright 2003 by the National Academy of Sciences. All rights reserved. National Research Council. (2003~. Estimating Eligibility arid Participation for the WIC Program: Final Report. Panel to Evaluate the USDA's Methodology for Estimating Eligi- bility and Participation for the WIC Program. Michele Ver Ploog and David M. Betson, editors. Committee on National Statistics, Division of Behavioral and Social Sciences and Education. Washington, DC: The National Academies Press.
THE NATIONAL ACADEMIES Advisers to the Nation on Stienre, Engineering, and Medicine The National Academy of Sciences is a private, nonprofit, self-perpetuating society of distinguished scholars engaged in scientific and engineering research, dedicated to the furtherance of science and technology and to their use for the general welfare. Upon the authority of the charter granted to it by the Congress in 1863, the Academy has a mandate that requires it to advise the federal government on scientific and technical matters. Dr. Bruce M. Alberts is president of the National Academy of Sciences. The National Academy of Engineering was established in 1964, under the charter of the National Academy of Sciences, as a parallel organization of outstanding engineers. It is autonomous in its administration and in the selection of its members, sharing with the National Academy of Sciences the responsibility for advising the federal govern- ment. The National Academy of Engineering also sponsors engineering programs aimed at meeting national needs, encourages education and research, and recognizes the supe- rior achievements of engineers. Dr. Wm. A. Wulf is president of the National Academy of Engineering. The Institute of Medicine was established in 1970 by the National Academy of Sci- ences to secure the services of eminent members of appropriate professions in the ex- amination of policy matters pertaining to the health of the public. The Institute acts under the responsibility given tO the National Academy of Sciences by its congressional charter to be an adviser to the federal government and, upon its own initiative, to identify issues of medical care, research, and education. Dr. Harvey V. Fineberg is presi- dent of the Institute of Medicine. The National Research Council was organized by the National Academy of Sciences in 1916 to associate the broad community of science and technology with the Academy's purposes of furthering knowledge and advising the federal government. Functioning in accordance with general policies determined by the Academy, the Council has become the principal operating agency of both the National Academy of Sciences and the Na- tional Academy of Engineering in providing services to the government, the public, and the scientific and engineering communities. The Council is administered jointly by both Academies and the Institute of Medicine. Dr. Bruce M. Alberts and Dr. Wm. A. Wulf are chair and vice chair, respectively, of the National Research Council. www.national -academies.org
PANEL TO EVALUATE THE USDA'S METHODOLOGY FOR ESTIMATING ELIGIBILITY AND PARTICIPATION FOR THE WIC PROGRAM DAVID M. BETSON (Chair), Department of Economics, University of Notre Dame PAUL BUESCHER, Statistical Services Branch, North Carolina State Center for Health Statistics ALICIA CARRIQUIRY, Department of Statistics, Iowa State University JANET CURRIE, Department of Economics, University of California, Los Angeles JULIE DaVANZO, RAND, Santa Monica, California JOHN F. GEWEKE, Department of Economics, University of Iowa DAVID GREENBERG, Department of Economics, University of Maryland, Baltimore County ROBERT P. INMAN, Wharton School, University of Pennsylvania JAMES LEPKOWSKI, Institute for Social Research, University of Michigan JOHN KARL SCHOLL, Institute for Research on Poverty, University of Wisconsin-Madison CAROL WEST SUITOR, Consultant, Northfield, Vermont MICHELE VER PLOEG, Studly Director CONSTANCE F. CITRO, Senior Program Officer EMIL CASEY, Research Assistant MICHAEL SIRI, Project Assistant v
COMMITTEE ON NATIONAL STATISTICS 2002-2003 JOHN E. ROLPH (Chair), Marshall School of Business, University of Southern California JOSEPH G. ALTONII, Department of Economics, Yale University ROBERT BELL, AT&T Laboratories, Florham Park, New Jersey LAWRENCE D. BROWN, Department of Statistics, University of Pennsylvania ROBERT M. GROVES, Survey Research Center, University of Michigan JOEL HOROWITZ, Department of Economics, Northwestern University WILLIAM KALSBEEK, Department of Biostatistics, University of North Carolina ARLEEN LEIBOWITZ, School of Public Policy Research, University of California, Los Angeles THOMAS A. LOUIS, Department of Biostatistics, Johns Hopkins University VIIAYAN NAIR, Department of Statistics, University of Michigan DARYL PREGIBON, AT&T Laboratories, Florham Park, New Jersey KENNETH PREWITT, School of International and Public Affairs, Columbia University NORA CATE SCHAEFFER, Department of Sociology, University of Wisconsin-Madison MATTHEW D. SHAPIRO, Department of Economics, University of Michigan ANDREW A. WHITE, Director v'
Acknowledgments The Panel to Evaluate the USDA's Methodology for the Estimating Eligibility and Participation for the WIC Program wishes to thank the many people and institutions that contributed to the preparation of the final report. The panel especially wishes to thank the staff of the Food and Nu- trition Service (ENS) of the U.S. Department of Agriculture (USDA) lay Hirschman, Cindy Long, Dawn Aldridge, and Stephanie Schmidt, for their willingness to answer the panel's numerous questions on the rules and regu- lations of the WIC program. We also wish to acknowledge David Smallwood for his role as a liaison with the Economic Research Service (ERS), the funding agency within USDA for this project. As chair of the panel, I would like to thank my fellow panel members for their commitment and patience through the numerous drafts of this report. Their timely and constructive involvement has made this report possible. While every member of the panel contributed to the final report, I would like to thank panel members lanes Currie and Karl Scholz for con- ducting numerous simulations and calculations using the Survey of Income and Program Participation (SIPP) that appear in this report. I would also like to thank Alicia Carriquiry and Carol Suitor for calculating the preva- lence of nutritional risk under alternative definitions using the Continuing Survey of Food Intake by Individuals. . . v''
vIll i, ACKNOWLEDGMENTS To prepare and draft this final report, the panel convened two meet- ngs. The first meeting after the release of the panel's interim report was held on March 19 and 20, 2002, in Washington, DC. During the open session of this meeting, the panel heard two presentations of papers it had commissioned. One paper, by Alison lacknowitz of RAND, reviewed cur- rent rates of breastSeeding among new mothers and data for estimating these rates. The second paper, by Aaron Yelowitz of the University of Ken- tucky, examined variability in family income around the time of a child's birth. The second meeting of the panel was a two-day retreat held lune 17 and 18, 2002, at Woods Hole, Massachusetts. At this closed meeting, the panel finalized the conclusions and recommendations of the report draft. Central to the work of the panel was the original examination of data from the Current Population Survey (CPS) and SIPP. Linda Giannarelli, Joyce Morton, Paul Johnson, and Laura Wheaton of the Urban Institute assisted the panel's examination ofthe CPS data and output from the TRIM model. The panel would also like to thank Sheila Zedlewski of the Urban Institute for making this work possible. The panel would like to thank Molly Dahl, University of Wisconsin-Madison, for the assistance she pro- vided the panel in its examination of the SIPP data. A staff that was both professional and a pleasure to work with assisted the panel. The panel's work could not have been completed without the admirable assistance of Michele Ver Ploog, the study director. Her initial drafts of many of the sections of the report and attention to the overall management of the project were invaluable to the panel. We would also like to thank Constance Citro, senior program officer at the National Re- search Council, for her sound advice and counsel during the drafting of the final report. Finally, the panel acknowledges the able research and project assistance provided by lamie Casey and Michael Siri. This report has been reviewed in draft form by individuals chosen for their diverse perspectives and technical expertise, in accordance with proce- dures approved by the National Research Council (NRC) Report Review Committee. The purpose of this independent review is to provide candid and critical comments that will assist the institution in making its pub- lished reports as sound as possible and to ensure that the report meets institutional standards for objectivity, evidence, and responsiveness to the study charge. The review comments and draft manuscript remain confi- dential to protect the integrity of the deliberative process. We wish to thank the following individuals for the review of this report: Howard Chernick, Department of Economics, Hunter College, and the Graduate Center, City
ACKNOWLEDGMENTS AX University of New York; Barbara Devaney, Mathematica Policy Research, Princeton, NI; Peter Germanis, American Enterprise Institute, Washing- ton, DC; Gordon H. Lewis, Heinz School of Public Policy and Manage- ment, Carnegie Mellon University; Arleen A. Liebowitz, Department of Policy Studies, University of California, Los Angeles; Randall I. Olsen, Cen- ter for Human Resource Research, Ohio State University; and Virginia A. Stallings, Joseph R. Stokes Research Institute, Nutrition Section, The Children's Hospital of Philadelphia. Although the reviewers listed above have provided many constructive comments that greatly improved the final report, they were not asked to endorse the conclusions and recommendations nor did they see the final draft of the report prior to its release. The review of this report was overseen by Robert Moffitt, Department of Economics, Johns Hopkins University. Appointed by the National Research Council he was responsible for mak- ing certain that an independent examination of this report was conducted in accordance with institutional procedures and that all review comments were carefully considered. Responsibility for the final content of this report rests entirely with the authoring committee and the institution. David M. Betson, Chair Panel to Evaluate the USDA's Methodology for Estimating Eligibility and Participation for the WIC Program
Contents EXECUTIVE SUMMARY Panel Charge and Approach, 2 The WIC Program, 3 Estimating Eligibility and Participation, 3 Alternative Estimation Strategies, 6 1 INTRODUCTION Panel Charge, 14 Timeline of Panel Work, 15 Plan of the Report, 16 2 OVERVIEW OF WIC AND THE CURRENT ESTIMATION METHODOLOGY Purposes of Estimating Eligibility and Participation, 19 WIC Eligibility, 23 Current Methods for Estimating Eligibility and Full-Funding Participation, 26 Summary, 33 3 ACCURACY AND SOURCES OF ERRORS Accuracy of the USDA Methodology, 34 x' 1 13 18 34
xI' Sources of Error, 38 Evaluating Current and Alternative Methods for Estimating Eligibility and Participation, 40 Summary, 41 CATEGORICAL ELIGIBILITY OF INFANTS AND CHILDREN Explanation for the Undercount of Infants, 43 Adjustment Procedure to Improve the Accuracy of the Counts of Infants and Children, 46 SIPP-Based Estimates of the Numbers of Infants and Children, 48 Summary, 49 INCOME AND ADIUNCTIVE ELIGIBILITY OF INFANTS AND CHILDREN Income and Adjunctive Eligibility Rules, 51 Impact of Monthly Income and Adjunctive Eligibility, 58 Summary, 67 6 ESTIMATION OF THE NUMBER OF INCOME-ELIGIBLE PREGNANT AND POSTPARTUM WOMEN Pregnant Women, 69 Postpartum Women, 73 SIPP-Based Estimates of Pregnant and Postpartum Women, 81 Summary, 81 ESTIMATING ELIGIBILITY BASED ON MEETING NUTRITIONAL RISK CRITERIA Critique of Current Method, 86 Possible Methods to Estimate Nutritional Risk, 87 Cost-Benefit Analysis of Assessing the Dietary Risk of WIC Applicants for Determining Eligibility, 105 Summary, 110 CONTENTS 42 50 68 83
CONTENTS 8 ESTIMATING WIC PARTICIPATION AMONG ELIGIBLE PEOPLE Data Sources to Estimate WIC Participation Among Eligible People, 114 WIC Participation Among Eligible People, 123 Factors Correlated with WIC Participation, 128 Summary, 131 9 OPTIONS FOR ESTIMATING ELIGIBILITY AND PARTICIPATION Alternative Strategies for Predicting Eligibility, 133 Predicting WIC Full-Funding Participation, 147 Summary, 158 1 0 SUMMARY Estimating Eligibility, 159 Estimating Full-Funding Participation, 162 REFERENCES APPENDICES A Data Sources and Coverage Issues B Nutritional Screening and Budget Estimates C Reconciling Different Estimates of Income and Adjunctive Eligibility D Biographical Sketches of Panel Members and Staff x''' 113 133 159 163 169 179 188 199
